This invention relates to a stencil printing method and to an apparatus therefor.
FIG. 18 is a schematic illustration of an outline of a conventional stencil printing device in which a plating section and a printing section are accommodated in a single apparatus. In FIG. 18, designated as 70 is a stencil master, 71 a master feeding section having a roll of the stencil master before perforation, 72 a plating section having a platen roller 72a and a thermal head 72b, 73 a cutter mechanism for cutting a perforated stencil master 70, 74 a transferring mechanism for the stencil master, 75 a printing section, 76 a plate cylinder, 76a a peripheral surface, 77 a plate discharging section and 78 is a printing paper. With this device, a stencil master 70 fed from the master feeding section 71 is thermally perforated in the plating section. The perforated stencil master 70 is transferred by the transferring mechanism 74 to the plate cylinder of the printing section and is cut by the cutter mechanism 73 into a sheet of the stencil master. This is then wound around the outer peripheral surface 76a of the plate cylinder 76. The printing paper 78 is fed to the printing section 75 and is printed there. After printing, the master used is discharged to the plate discharging section 77.
As shown in FIG. 18, however, the stencil printing master (master paper) has been hitherto cut each time the master is prepared. Therefore, when the cut stencil master is thin, problems are caused because of difficulty in transferring within the apparatus, in mounting to the plate cylinder and in discharging the master (namely in handling of the thin master).
To overcome the drawbacks, JP-A-H2-73987 proposes a stencil master printing device in which a master feeding and discharging section for a stencil master and a plating section are provided on a periphery of a plate cylinder and in which the stencil master is subjected, without being cut, to plating, mounting, printing and discharging operations as an elongated state. FIG. 19 is a side sectional view showing the stencil printing device. The device has a plate cylinder 80d attached to a rotary side plate 80c of a plate cylinder unit 80. A plate feeding and discharging unit 81 is also mounted on the rotary side plate 80c at a location adjacent the plate cylinder 80d. The plate cylinder unit 80 is rotatable relative to an ink feeding means 87 inserted into the rotary cylinder 80d. The plate feeding and discharging unit 81 has a master feeding section 83 for storing a stencil master 82 in a rolled state, a platen roller 84, a thermal head 85 and a discharging roller 86 for winding a used master therearound. The plate cylinder unit 80 has a peripheral wall 80a a part 80b of which is constructed so as to be ink permeable. An ink fed from the ink feeding means 87 is fed through the part 80b to a printing paper (not shown).
With the stencil master printing device described in the above publication, however, since even the thermal head of the plating section is mounted on the plate feeding and discharging unit, the plating section becomes so heavy that the rotation of the plate cylinder unit cannot be smoothly performed. Additionally, there are defects that it is difficult to install wiring for feeding signals for the thermal head and that foreign matters such as paper powder are adhered to the thermal head to cause perforation troubles.
To overcome these defects, JP-A-H6-247024 proposes an apparatus as shown in FIG. 20, in which perforation means is disposed outside of a rotation system of a plate cylinder and is fixed to a body of the apparatus. In this case, it is easy to install wiring for a thermal head. In FIG. 20, designated as 1 is a plate cylinder unit, 4 a shaft, 8 a plate cylinder, 9 an ink permeable peripheral wall portion, 10 an ink feeding unit, 20 a plate feeding and discharging unit, 21 a stencil master, 22 a master feeding section, 23 a platen roller, 24 a discharged plate winding section, 30 a thermal head unit, 31 a thermal head and 31' is the thermal head in an advanced position.
In the above device, too, the feeding and discharging unit 20 including the rolled master, platen roller opposite the thermal head, and parts for the discharge of plates is disposed outside the plate cylinder 8 for rotation therewith, the weight is very large. Also, similar to the case of FIG. 19, a pressure roller for pressing the printing paper to the master attached to the plate cylinder is required to perform a motion of significantly departing from the plate cylinder each one revolution of the plate cylinder in order to avoid the collision against the feeding and discharging unit. This causes problems of enlargement of the printing apparatus, generation of noises, and complication of the apparatus. While the press roller might be arranged to have a large diameter and is provided with a recess to escape from the rolled master, etc., enlargement and cost-up of the apparatus are unavoidable.
A further proposal has been made in which the rolled master is disposed inside the plate cylinder. In this case, it is necessary for the ink roller disposed inside the plate cylinder to pass over the bar in each one revolution of the plate cylinder. This causes the generation of noises and complication of the apparatus.